1. Field of the Invention
Embodiments of the present invention relate generally to optical communication systems and components and, more particularly, to a liquid crystal-based optical switch and attenuator.
2. Description of the Related Art
In optical communication systems, it is sometimes necessary to perform 1×2 switching of an optical signal, where an input light beam enters an optical switching device through an input fiber and is directed to one of two output fibers. There are also more complicated optical switches, such as 2×2, 1×N, and N×N optical switches, which are realized by combining several 1×2 optical switches.
In addition to routing of signals by optical switches, attenuation of signals in optical communication systems is also advantageous, for example in an optical communication system that employs wavelength division multiplexing (WDM). In such an optical system, information is carried by multiple channels, each channel having a unique wavelength. WDM allows transmission of data from different sources over the same fiber optic link simultaneously, since each data source is assigned a dedicated channel. The result is an optical communication link with an aggregate bandwidth that increases with the number of wavelengths, or channels, incorporated into the WDM signal. In this way, WDM technology maximizes the use of an available fiber optic infrastructure, such that what would normally require multiple optic links or fibers instead requires only one.
In practice, different wavelength channels of a WDM signal typically undergo asymmetrical losses as they travel through an optical communication system, resulting in unequal intensities for each channel. Because these unequal intensities can compromise the integrity of the information carried by the WDM signal, an optical device or array of optical devices is typically used in WDM systems to perform wavelength-independent attenuation.
While switching and attenuation of optical signals are known in the art, each of these operations is performed by a different optical device. The use of an optical device to perform switching and another device to perform attenuation in an optical communication system increases the size and complexity of the system, makes erosion of signal quality more likely due to misalignment of the optical devices, and requires a first independent control signal to complete the switching function and a second independent control signal to complete the attenuation function. Accordingly, there is a need in the art for an optical switch for use in an optical network capable of performing both switching and attenuation of an optical signal.